Hot-blast dry kiln



B.,L. GRONDAL.

HOT BLAST DRY KILN. APPLICATION FILED NOV. 2, 1920.

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ATTORNEY row L 6/0/76227/ Patented Dec. 5, i922.

BROR L. GRONDAL, OF SEATTLE, WASHINGTON, ASSIGNOR TO NORTH COAST DRY-KILN COMPANY, OF SEATTLE, WASHINGTON, A CORPORATION OF WASHINGTON.

HOT-BLAST DRY KILN,

Application filed November 2, 1920. Serial No. 421,214.

To all whom it may concern Be it known that I, Bron L. GRoNDAL, a citizen of the United States, residing at Seattle, in the county of King and State of Washington, have invented certain new and useful Improvement in Hot-Blast Dry Kilns, of which the following is a specification.

This invention relates to kilns which are designed, more especially, for drying lumher and shingles.

The object of my invention is to produce apparatus of this character whereby lumber or the like may be economically and rapidly seasoned or dried in a more uniform and thorough manner than hitherto.

The invention consists in the novel construction, adaptation and combination of parts as will be hereinafter described and claimed.

In the accompanying drawings, Figure 1 is a transverse vertical section of a dry-kiln embodying the present invention; and Fig. 2 is a fragmentary plan view of the same, the kiln structure being shown in horizontal section. Fig. 3 is a detail longitudinal view of one of the steam-blast nozzles, shown to approximately full size.

In said drawings, the reference numeral 5, 5 designate the side walls, 6 is the back wall and 7 is the roof of a one-compartment dry-kiln which may be constructed of any suitable material and is provided at the front with the usual door way, not shown.

Extending longitudinally into the kiln chamber is a track comprising rails 8 which are supported up n spaced posts 9.

Said track is disposed to be closer to the side wall 5 than to the other wall 5 Mounted upon said track rails are trucks 10 carrying bunks, such as 11, upon which is placed a load of material to be dried or seasoned. I illustrate in Fig. 1 aload 12 of lumber stacked ontheir edges, the adjacent vertical rows being separated by strips 12 to afiord vertical channels 14 intermediate such rows for the passage of a drying medium composed of air and water vapor through the load.

By locating the track, as above'mentioned, in a non-central position within the kiln the load of material serves as a partition to divide the kiln interior above the track into rising and diving flues 15 and 16, res ectively, at opposite sides of the load. aid

fiues are communicatively connected by a horizontal passage 17 obtaining above the load. Subjacent to said track is, a floor 18 which extends, desirably, in an upwardly inclined direction from the wall 5 to the bottom of a vertical partition 19 extending upwardly into the flue 15 at a short distance from the wall 5 20 represents an apron which is disposed above said floor and inclines downwardly from the wall 5, as shown, to afford a longitudinal slot 21 below the outer edge of the apron and above the floor.

Located below the floor and the throat 22 t0 the rising flue 15 is a series of pipes 23, conventionally known as a coil, through which is circulated steam of a high temperaturesay at about 290 F. Such coil receives its supply of steam as by a pipe 24', Fig. 2, from a boiler, not shown, and serves to repeatedly heat the hereinafter referred to lumber drying medium.

Located at intervals beneath the floor 18 is a plurality of substantially horizontal tubes 25 arranged transversely of the kiln and communicating by floor openings 26 with the space below the apron 20.

27 represents a pipe leading from a steam boiler not shown, and having branches 28 extending axially into the respective tube 25. Provided on the end of each of the pipe branches 28 is a nozzle 29. As shown in Fig. 3, a nozzle 29 is formed interiorly with a passage having a cylindrical mouth 30 whence it extends, as at 31, in a conoidal form to a relatively small orifice 32 of the vena contracta socket 33 within which is engaged the respective pipe 28. A et of steam lssuin through the orifice 32 at an extreme y high velocity into the conoidal portion 31 of gradually increasing diameter results in the expansion of such jet until the cylindrical portion 30 is reached and the jet is thereby caused to be delivered at a high velocity in a stream axially through the respective tube 25 to the coils as denoted by darts m in Fig. 1.

By thus discharging the steam across the lower portion of the chamber and by reason of the relative positions and arrangement of the apron 20, floor 18 and the tubes 25, a circulatory impulse is given to the drying medium to take a general course about and through the stack of lumber as indicated by feathered arrows in Fig. 1.

Such circulation of the drying medium is promoted by the inductive properties of the jets of steam within the several tubes, causing the currents to pass through the hot pipe COllS thereby heating said medium so that the specific gravity of the same is relatively less in the rising flue 15 than inother parts of the chamber.

34; represents a pipe located adjacent to the bottom of the kiln chamber and afilording communication between the interior of the same and the outside of the kiln where by the pressure within the kiln is main tained at substantially that of the external atmosphere.

By reason of the position of the load of lumber closer to one side of the chamber than to the other side, the capacity of the diving flue 16 is accordingly less than that of the rising flue, hence the tendency is for a portion of the drying medium to pass through the interstices between the lumber. When the load is stacked with the lumber upon their edges as illustrated inthe drawings the general courses of the currents passing through the load will be downwardly.

It is to be understood, however, that the lumber may if desired be piled flatwise upon the car, in which event the general course of the currents will be horizontal through the load.

The construction, arrangement and operation of the invention will, it is thought be understood from the foregoing description.

What I claim is,

1. In a hot-blast dry kiln having a partition dividing the interior thereof into upper and lower compartments which communicate with each other through an opening at one side of said partition, a heat-' ing coil provided in the lower of said compartments, a series of tubes also provided in said lower compartment and communicatively connected through passages in said partition with the space above the latter in the upper compartment, pipes extending axially into the respective tubes and directed toward said heating coil, and means to supply steam through said pipes to inductively draw the work-drying medium through said passages and tubes and deliver the same against the coil thereby creating a circulatory movement of the drying medium within the kiln.

'2.'A circulatory system for a hot-blast dry-kiln adapted to receive a load of lumber to be dried, comprising a series of blast nozzles located to be below the load, a par tition disposed to be between the load and said nozzles, said partition serving to direct downwardly currents from one side of the load to said nozzles and from the latter to the other side of the load, means to supply steam to said nozzles to render the circulation of the drying medium within the kiln,

ments having communicative connection with a car adapted to have a load of lumher thereon, and a track provided in the kiln for said car whereby the load is located to afford a relatively wide upflow flue at I one side of the load and a narrow downfiow flue at the other side thereof, of a heating coil disposed below said upflow flue, a series of steam nozzles directed toward said coil, means to supply steam under pressure to said nozzles, and means provided so as to be intermediate the load and said nozzles whereby currents of the drying medium are guided from said downfiow flue to the nozzles, said means also serving to guide such medium from said coil to the upflow flue when the medium is impelled by steam issuing from said nozzles.

4. In a hot-blast dry-kiln, the combination with a partition dividing the interior of the kiln into upper and lower compartwith each other by means of passages located adjacent to the respective side Walls of the kiln, communicative connections between the external atmosphere and said lower compartment for regulating the pres- 9 sure obtaining within the kiln, a heating coil provided in said lower compartment and in proximity of one of said passages,

a series of pipes disposed below the other of said passages and directed toward said heating coil, and means to supply steam under high pressure to said pipes whereby a circulation of the work-dry ng medium is efiected by inductively causing the same to be drawn downwardly into the lower compartment through the last mentioned passages, then laterally and returning by the other passage tosaid upper compartment.

5. In a hot-blast dry-kiln having a track extending therein and disposed to be closer to one side of the kiln than the other, a partition extending beneath the track from one side wall, said partition being provided adjacent to the latter with apertures, an inclined apron disposed above the partition at the apertured side thereof, the lower side of said apron being spaced above said partition to afford a passage therebetween, transversely arranged pipes provided below said partition, casings for said pipes, one of said casings communicating at one end with each of said apertures, the other ends of said casings being open, means to supply steam through said pipes whereby currents of the work-drying medium are drawn through said apertures and casings to ascend into the space above the partition at the side of the latter remote from the apertures thereof, and means extending from the outside of the kiln into the space below said partition for the purpose of maintaining the interior oi the kiln at substantially the pressure of the downflow flue at the other side thereof and with a horizontal passage connecting said flues above the material, a heating means provided below the'upflow fiue, a series of tubes provided below the downflow flue and com municating with the latter, steam conducting pipes extending axially into the respective tubes, and nozzles for the respective pipes, each of said nozzles having a passage extending therethrough and provided with a small orifice adjacent its inlet end, said passage beyond said orifice being of a concidal shape and terminating in a cylindrical portion at the discharge end whereby steam issues therefrom expansively to inductively convey the drying medium from the downflow flue through the respective tube to the flue.

Signed at Seattle, Washington, this 20th day of October, 1920.

BROR L. GRONDAL. Witnesses:

PIERRE BARNEs, MARGARET G. SUPPLE.

T25 heating coil and eventually to the upflow 

